Regulating stress response to promote postnatal beta-cell function and survival

调节应激反应以促进产后 β 细胞功能和存活

基本信息

批准号：
10366079
负责人：
Guoqiang Gu
金额：
$ 48.71万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-04-01 至 2025-03-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10366079
关键词：
5&apos Flanking Region ATF6 gene Acetylation Adult Affect Anabolism Attenuated B Cell Proliferation Beta Cell Cell Death Cell Line Cell Survival Cell Transplantation Cell physiology Cells Cessation of life ChIP-seq Complex Development Diabetes Mellitus Disease Down-Regulation Failure Family Financial compensation Functional disorder Gene Activation Gene Expression Genes Genetic Transcription Glucose Glucose Intolerance Goals Heat-Shock Response Histone Deacetylase Histone Deacetylation Histones Homeostasis Human Hyperglycemia Hypoglycemia Immunodeficient Mouse In Vitro Insulin Insulin Resistance Interruption Islet Cell Islets of Langerhans Knowledge Lead Link Mediating Messenger RNA Metabolic Metabolic stress Mitochondria Modeling Molecular Molecular Target Mus Myelin Non-Insulin-Dependent Diabetes Mellitus Obesity Open Reading Frames Output Oxidative Stress Peripheral Persons Physiology Process Production Proinsulin Proteins Proteomics Publishing Reactive Oxygen Species Regulation Role Stress Structure of beta Cell of islet Testing Tissues Translations Up-Regulation Workload biological adaptation to stress blood glucose regulation gain of function gene product glucose metabolism improved in vivo in vivo evaluation insulin secretion islet islet stem cells knock-down novel paralogous gene postnatal prevent recruit response stressor transcription factor transcriptome sequencing

项目摘要

Workload-induced pancreatic islet β-cell dysfunction, loss-of identity, and cell death, commonly known as β-cell failure, is the hallmark of type 2 diabetes (T2D). This disease usually starts with obesity-induced insulin resistance, when peripheral tissues need higher levels of circulating insulin for glucose storage and usage. Islet β-cells compensate by expanding β-cell mass and increasing insulin output per cell, which requires upregulated insulin biosynthesis and oxidative glucose metabolism. These produce unfolded proinsulin in the ER and reactive oxygen species (ROS) in mitochondria, which at high levels can decimate β cells. Thus, β cells constantly activate stress response by stimulating the activity of several early-stage SRGs, including Atf6, IRE1, PERK, Hsf1, and Nurf2, to lead to: 1) attenuated overall protein translation; 2) enhanced translation of some SRG mRNAs that have special features such as upstream open reading frame (uORF) 5’ to the main ORF; 3) upregulated expression of some late-stage SRGs. The overall effect of these responses is to remove unfolded proteins/ROS for proteomic homeostasis and sustainable β-cell function. However, over-activating some late-stage SRGs such as Atf4 and Hsps induces β-cell failure by turning on some proapoptotic genes or by exceedingly lowering overall protein translation. Thus, it is imperative for β-cells to limit the levels of failure- causing SRGs for sustainable high-level of insulin output. An emerging model from our recent published findings is that a transcriptional complex containing Myt TFs and Sin3 can selectively repressing these failure- causing SRGs. Myt TFs are a family of three myelin transcription factors (Myt1, 2, and 3) highly expressed in islet cells. Sin3, including Sin3a and Sin3b, is a coregulator that represses transcription by recruiting histone deacetylases (HDACs) to modify histones. We showed that Myt TFs and Sin3 can form a transcription complex in β cells. Inactivating these genes in mouse and human β cells causes cell dysfunction and/or death while overactivating late-stage β-cell-failure-causing SRGs but not early stage SRGs. Intriguingly, Myt TFs, particularly Myt3, is induced by obesity-related stressors in mouse and human β cells, likely mediated by an uORF in 5’ flanking region of Myt3 mRNA. Importantly, MYT3 down-regulation accompanies human β-cell failure in T2D development. Our overarching hypothesis is that the stress-responsive Myt TFs, particularly Myt3, promote -cell function/survival by repressing late-stage SRGs via Sin3-mediated histone de-acetylation under both normal physiology and metabolic stress. Aim 1 will establish how MYT TFs repress SRG expression in a human β cell line and how manipulating MYT-TF levels will affect primary human β-cell function and survival. Aim 2 will define how metabolic stressors up-regulate Myt3 production and how this upregulation enable β-cell compensation under metabolic stress. We expect to uncover a tunable mechanism that can be explored for preventing/delaying β-cell failure and T2D.

工作负荷引起的胰岛 β 细胞功能障碍、身份丧失和细胞死亡，通常称为 β 细胞衰竭是 2 型糖尿病 (T2D) 的标志，这种疾病通常始于肥胖引起的胰岛素。当外周组织需要更高水平的循环胰岛素来储存和使用葡萄糖时，就会产生抵抗力。胰岛 β 细胞通过扩大 β 细胞质量和增加每个细胞的胰岛素输出来进行补偿，这需要上调胰岛素生物合成和氧化葡萄糖代谢，在体内产生未折叠的胰岛素原。线粒体中的 ER 和活性氧 (ROS)，高水平时可以杀死 β 细胞。细胞通过刺激几个早期 SRG 的活性不断激活应激反应，包括 Atf6、 IRE1、PERK、Hsf1 和 Nurf2，导致：1) 整体蛋白质翻译减弱；2) 蛋白质翻译增强；一些 SRG mRNA 具有特殊功能，例如主链 5’ 端的上游开放阅读框 (uORF) ORF；3) 一些晚期 SRG 的表达上调。这些反应的总体效果是消除。未折叠的蛋白质/ROS 用于蛋白质组稳态和可持续的 β 细胞功能。一些晚期 SRG，例如 Atf4 和 Hsps，通过开启一些促凋亡基因或诱导 β 细胞衰竭因此，β细胞必须限制失败的水平。 SRG 导致可持续的高水平胰岛素输出。我们最近发表的一个新兴模型。研究结果表明，包含 Myt TF 和 Sin3 的转录复合物可以选择性地抑制这些失败。引起 SRG 的 Myt TF 是三个髓磷脂转录因子（Myt1、2 和 3）的家族，在 Sin3，包括 Sin3a 和 Sin3b，是一种通过招募组蛋白来抑制转录的共调节因子。我们发现 Myt TF 和 Sin3 可以形成转录复合物。使小鼠和人类 β 细胞中的这些基因失活会导致细胞功能障碍和/或死亡。过度激活导致晚期 β 细胞衰竭的 SRG，但不会过度激活早期 SRG，有趣的是，Myt TF，特别是 Myt3，是由小鼠和人类 β 细胞中与肥胖相关的应激源诱导的，可能是由 Myt3 mRNA 5' 侧翼区域中的 uORF 重要的是，MYT3 下调伴随着人类 β 细胞。我们的总体假设是压力反应性 Myt TF，尤其是 T2D 发育的失败。 Myt3，通过 Sin3 介导的组蛋白去乙酰化抑制晚期 SRG，从而促进  细胞功能/存活目标 1 将确定 MYT TF 如何抑制 SRG。人 β 细胞系中的表达以及操纵 MYT-TF 水平将如何影响原代人 β 细胞目标 2 将定义代谢应激源如何上调 Myt3 的产生以及这是如何进行的。我们期望发现一种可调节的机制。可以探索预防/延缓 β 细胞衰竭和 T2D 的方法。